.sub{
  width: 30vw;
  height: 10vw;
  border: 0.5vw solid black;
  border-radius: 3vw;
  text-align: center;
  line-height: 10vw;
  font-size: 5vw;
  margin-top: 5vw;
  margin-bottom: 8vw;
  letter-spacing: 1vw;
}